PURPOSE: To make the vibration loss larger and to improve regidity by impregnating polypropylene to the long fiber glass mat, and by compositing the speaker horn as the compound layer-shaped construction with polypropylene.

CONSTITUTION: A glass fiber 2 with average fiber length of about 50mm is mounted on a polypropylene with thickness of 1mm or polymerization sheet 1, is vibrated in the X-Y circle direction, a glass fiber 2 is in parallel at random, after the plural fibers are overlapped and are heated by a remote infrared-ray heater heater 3 at 130∼150°C, a compound sheet 5 is obtained by laminating and molding through rollers 4 and 4'. Further, after the compound sheet 5 is cut and the plural sheets are overlapped and heated at the thick part, they are pressed with room temperature metal molds 6 and 7 at the pressure of about 120kg/cm2, and then, polypropylene in the fluidized condition is deformed and pressed along the mold at the recessed part. The sugged thick speaker horn is obtained by cooling and setting this.